The news came as the Paris prosecutor said four men suspected of providing logistical support to one of the terror attackers have been charged with associating with terrorism – the first charges handed out for the attacks that left 20 people dead, including three gunmen.
French prime minister Manuel Valls said the government will spend €425 million (£326m) on counter-terrorism over three years in response to the Paris attacks. Three police officers were among those killed by the gunmen.
France will also strengthen its intelligence apparatus, introducing a measure to make it easier to tap phones, he said. In addition, 3,000 people with ties to France – some at home, others abroad, will be monitored by anti-terror surveillance agents.
Outlining a web of phone calls, shared keys and prison friendships, Paris prosecutor Francois Molins said the four suspects – all in their 20s, all arrested in the Paris region – were handed preliminary charges overnight and will be jailed until a further investigation.
The prosecutor identified the suspects only as Willy P, Christophe R, Tonino G and Mickael A.
Three of the men are suspected of buying weapons for Amedy Coulibaly and one kept them at his house.
Coulibaly shot and killed a police officer on 8 January on the outskirts of Paris and then a day later killed four hostages at a kosher supermarket before being killed in a police raid.
Three of the four men charged had criminal records. At least one met Coulibaly in prison, Mr Molins said.
Coulibaly himself had met Cherif Kouachi, one of the two brothers who killed 12 people at the Parisian satirical magazine Charlie Hebdo, in prison. The DNA of Mickael A was found on a revolver in Coulibaly’s flat and on a glove the gunman wore in the supermarket. Mr Molins said Mickael A had 18 phone contacts with Coulibaly on 6 January.
The lawyer for one of those charged said his client was unaware of any terrorist plot and was afraid of Coulibaly.
Lawyer Fabrice Delinde told a French TV news television channel the gunman “terrorised my client” and intimidated him into helping. He would not identify his client for his own security.
Mr Molins said authorities in France are working with other countries to search for more possible accomplices.
They are especially trying to uncover who was responsible for the posthumous video of Coulibaly, which was edited and released days after he and brothers Said and Cherif Kouachi died in stand-offs with police. In the video, Coulibaly pledges allegiance to the Islamic State group and explains how the attacks were co-ordinated.
France has repeatedly strengthened its counter-terrorism laws over the years. One measure, which is expected to be activated in the coming weeks, would allow administrative authorities to ask internet service providers to block sites that glorify terrorism.
Meanwhile, France’s cyber-vulnerabilities have come into view. Interior minister Bernard Cazeneuve said Islamic extremist hackers have claimed responsibility for more than 1,300 attacks on French civilian and military websites since the Paris terror attacks. The low-grade vandalism, such as altering websites or home pages, was to show sympathy with the terrorists.